1. Field of the Invention
The invention is directed to an improved adjusting device in which a control motor is employed to adjust a control element via a gear, and to a method of producing the device.
2. Description of the Prior Art
Adjusting devices for internal combustion engines exist in which a control motor is meant to adjust a final control element via a gear. Since there is often little installation space available for the adjusting device in a motor vehicle, care must be taken to assure a small structural size. To enable a relatively small control motor to adjust the final control element quickly and precisely, a gear is provided between the control motor and the final control element. Because of the tight space, the gear must be as small as possible.
German Patent Disclosure DE 195 25 510 A1 and U.S. Pat. No. 5,672,818 show an adjusting device provided in the intake tube of an internal combustion engine. This adjusting device has a throttle valve shaft, which is pivotably supported in a throttle valve housing and on which a throttle valve is secured. A gas conduit extends through the throttle valve housing. By pivoting of the throttle valve shaft, the throttle valve opens and closes the gas conduit. A control motor can adjust the throttle valve via a gear located in a gearbox and having a plurality of gear wheels. A middle gear wheel is supported rotatably on a shaft that is solidly joined to the basic body of the throttle valve housing. The gearbox is covered by a cap. Since among other elements, parts of a position sensor are mounted on the cap, the cap must be positioned very precisely in the region of the position sensor. For this reason, and because manufacturing variations can never be avoided entirely, there must be play in the region between the cap and the cap-side end, toward the cap, of the shaft, especially in the radial direction. The shaft can therefore be firmly held only in the region of the basic body, while in the region of the cap, only loose bearing with a great deal of play can be achieved. This has the disadvantage that particularly at the point where the shaft emerges from the basic body, the shaft is burdened by major bending stresses and shear stresses, and an especially high-strength material must therefore be used for the shaft, or else the shaft would be so thick that the entire device would have to be unnecessarily large.